This invention relates to an exercise device and more particularly to an exercise device having a force applicator connected to a variable weight stack by means of a closed, hydraulic circuit.
Physical fitness has great importance for the human race--for the caveman, as a matter of life and death; and for today, as a contribution to the basic well-being of a person. The physically fit person can endure stress more efficiently and feel better while so doing. Physical fitness is also related to mental conditioning. For example, a chess player strives to be in good physical condition as a necessity before engaging in the serious competition of chess.
There are also more standard reasons to be in good physical condition. A person in good physical condition feels better and looks better than a person who is not in good condition.
Now there are studies which have determined that certain groups of muscles will develop in certain ways. With such interest in physical fitness is a corresponding interest in developing devices to assist in attaining the appropriate degree of physical fitness. These devices have an application in the science of kinesiology.
From the studies in kinesiology, it is known that to best train, tone or otherwise improve a group of muscles, a variable resistance is best applied over the full range of muscle function. This variable resistance is applied so that the most resistance is achieved at the high leverage points of the muscle. This is an especially critical training improvement for professional athletes and others who depend on physical skill for their livelihood.
Weight training with barbells is a well-known method of strengthening, toning or otherwise training muscles. However, such training can be inefficient. Much time is spent in changing weights rather than exercising. Also, it is quite easy to improperly vary the exercise and not exercise the required group of muscles. Furthermore, the full range of the muscle is not exercised in all cases when using a barbell. There are certain points of a barbell exercise which provide no resistance for the muscle or muscles involved, and hence are not as efficient in the working of the muscles.
A real danger in weightlifting occurs when a person loses control of the weight being lifted. Such loss of control can injure the lifter as well as persons in the vicinity of the lifter.
Also, in weight lifting, a variation in the lifting style can avoid exercising the muscles for which the particular exercise was designed. This variation circumvents the purpose of the exercise.
One attempt to overcome these problems involves the use of hydraulic exercise devices having an adjustment to restrict the flow of hydraulic fluid, thereby creating resistance without the use of a weights. The only problem solved in this fashion involves the changing of weights. The other standard problems of weightlifting still exist. Furthermore, the hydraulic factor can be easily overcome by moving with extreme slowness and avoiding the required strain and testing of the muscles as desired.
Appropriate devices are known which overcome the problems inherent in weight training. Simpler devices use a direct connection between an adjustable weight stack and a force applicator, which minimizes and simplifies the problems of changing weights. With such a direct connection, however, the problems of not exercising the proper group of muscles and not applying resistance over the full range of the muscle together with other problems still remain.
More complicated devices solve the problems of exercising the proper group of muscles by using a system of chains, gears, and cables to connect various force applicators to a variable weight stack. In this manner, resistance can be applied over the entire range of the muscle.
The more complicated devices cause a number of problems. Firstly, they are bulky and require a substantial amount of room for proper operation. Secondly, the cams, chains and cables, and gears require substantial maintenance and lubrication. The chains and cables have a tendency to stretch and upset the balance of the machine, which can result in the proper group of muscles not being exercised. Additionally, the substantial number of parts used, which leads to the bulkiness, prevents the device from having a plurality of uses. One of the most significant problems of the complicated devices is the cost.
Thus, it may be seen that there are many problems to be solved in the field of exercise devices.